[pdf] [ps] [txt]
An XML Implementation of the Genealogical Data Model
Hans Fugal (hans@fugal.net)
All commercial and freely available genealogical software today supports a
conclusional paradigm: Users do research and enter their conclusions in the
software. Genealogical research, when done well, is a process of first
collecting evidence and then making assertions that lead to conclusions.
Documenting the sources used to draw these conclusions is vital. The only
support software in the past has provided for recording such documentation was
a ``notes'' field; but now the modern genealogical commuminity is more aware
of the need for proper documentation, so most modern genealogical software
provides more advanced methods for doing so. However, many beginning
genealogists still document only as an afterthought or as an aside. The
conclusional paradigm fails to handle these and other documentation issues. In
1998, the Lexicon Working Group, created by GENTECH and the FGS, released an
RFC (Request For Comment) describing the Genealogical Data Model
(GDM)[1], which addresses these issues, and others, and provides a new
paradigm for understanding genealogical data and the genalogical research
process. The GDM is a valuable and sound model of genealogical information and
processes, with great potential for changing the way we store genealogical
information. While the GDM does not strive to change the way a professional
genealogist does research, the influence of software based on the GDM may
indeed change--for the better--the way an amateur genealogist does research.
The GDM is not a database schema or a data structure; it is simply a logical
data model. It was created as such to avoid being influenced by the details of
implementation or by the limitations of technology. The Lexicon Working Group
wished to leave implementation of the model up to other researchers and
developers.
My research project will implement the GDM using XML (Extensible Markup
Language.) Reaching a practical software implementation of the GDM requires the
following: (1) an internal data represntation that fits the GDM and (2) an
effective and standard scheme for communication between users and between
programs. My XML proposal addresses the communication requirements. It follows
the lead of GENTECH's LexML project. LexML was a project to develop an XML
implementation of the GDM. I was unable to find anything more than a mention of
the LexML project on the Web, so I contacted Beau Sharbrough, GENTECH
president, who told me that the project has seen little to no activity recently
and encouraged me to pursue the idea.
XML is ideal for an implementation of the GDM for several reasons: It is
human-readable, extensible, flexible, hierarchial, and a quickly growing
standard in the industry. Another significant reason is that the Church of
Jesus Christ of Latter-day Saints has announced their intentions to migrate to
XML for data storage and communication.[2] It is my desire to lay
some groundwork for that effort.
I will develop an XML DTD (Document Type Definition) that will describe the
GDM. The GDM is well-developed and concisely stated so creating an XML DTD
should be straightforward. There will be issues of implementation to
consider, and there may be some questions that will take serious deliberation.
When I come across these questions I will solicit the volunteer help of
GENTECH volunteers and the Lexicon Working Group, as well as other email
lists such as GEDCOM-L that may show interest. If the nature of the question
is appropriate, I will draw upon resources of the Family History department
faculty here at BYU.
The GDM leaves some areas for future research, namely the expert systems for
person names, place names, and dates. I will provide a basic implementation of
the data of these systems that will be easily extended or replaced by future
research in these areas, and should be able to handle common cases for most
basic (amateur-level) genealogical research. I do not intend for these systems
to be in final form--they will each require a great deal of research and
effort. I do hope to provide a basic and working implementation that can show
the potential for an XML representation of the GDM and which may prove to be a
useful foundation for these expert systems.
This XML implementation will be the first practical implementation of the GDM.
It may bring to light some problems or questions
about the GDM which can then be ironed out by the Lexicon Working Group. It
will allow for practical and standardized sharing of data represented by the
GDM and should prove to be valuable in continued research in genealogical data
and systems. This implementation will hopefully be a springboard to more
uses of the GDM including relational-database-driven software in the long
term. Such software will give the genealogist a great deal of power in
searching, organizing, and understanding data. It will more closely fit the
needs of professional researchers and if designed correctly will still be easy
for amateur researchers while instilling proper research practices as they
learn.
- 1
- Lexicon Working Group: GENTECH Genealogical Data Model,
http://www.gentech.org/gdm/ (1998)
- 2
- Randy Bryson, The Church of Jesus Christ of Latter-day Saints:
At the GENTECH 2001 Conference, Dallas, TX (2-3 Feb 2001)
Hans Fugal
2001-11-27